Apparatus for gauging the lengths of articles



Dec. 4, 1951 R. w. MUELLER ETAL 2,577,144

APPARATUS FOR GAUGING THE LENGTHS OF ARTICLES Filed Dec. 31, 1945 I 4 Sheets-Sheet 1 IJNVENTORS RW MUELLER R STECH ATTORNEY Dec, 4, 1951 R. w. MUELLER ETAL 2,577,144

APPARATUS FOR GAUGING THE LENGTHS OF ARTICLES 4 Sheets-Sheet 2 Filed Dec. 31, 1945 ATTORNEY w ml 9 N\ QN INVENTORS RW MUELLER P. STECH Dec. 4, 19511 R. w. MUELLER ETAL 2,577,144

APPARATUS FOR GAUGING THE LENGTHS OF ARTICLES Filed D60. 31, 1945 4 Sheets-Sheet 3 FIG. 7

INVENTO/PS RW MUELLER R. STECH A 7'TOPNE) Patented Dec. 4, 1951 V APPARATUS FOR. GAUGIN G TiIE LEN GTHS OF ARTICLES Baltimore, and Richard Raymond W. Mueller,

Stech, Govans, trlc Company,

Md., assignors to Western Elec- Incorporated, a corporation of New York New York, N. Y.,

Application December 31, 1945, Serial No. 638,568 6 Claims. (01. 175-183) This invention relates to apparatus for gaging the lengths of articles, and more particularly apparatus for gaging the lengths of potentiometer cards.

In the manufacture of potentiometers of a type including potentiometer cards, the potentiometer cards are sometimes formed by winding small insulated resistance wires on body members and connecting leads to particular intermediate turns of the resistance wires having a predetermined resistance therebetween. In some potentiometers it is required that there be a predetermined linear distance between the turns of the resistance wires to which the leads are attached. It is desirable to check the distances between the turns of the resistance wires prior to the assembly of the potentiometers so that the potentiometers need not be disassembled if the distances between such turns are outside allowable limits. In order to measure the distance between the turns of small wire, it is necessary to locate the particular intermediate turns to which the leads are connected, which has been difficult to do by visual inspection even with the aid of strong magnifying devices.

An object of the invention is to provide new and improved apparatus for gaging the lengths of articles.

Further objects of the invention are to provide new and improved apparatus for measuring the linear distance between turns of a potentiometercard to determine whether such distances lie within allowable limits.

An apparatus constituting a specific embodiment of the invention includes a gaging fixture in which a potentiometer card having a resistance wire wound around a body member thereof may be placed. A lead secured to the zero turn, which has other turns on both sides thereof, of the resistance wire is connected to a galvanometer and the card is slid along a stationary contactor, which also is connected to the galvanometer. When the zero turn of the resistance wire contacts the contactor-the galvanometer will indicate a larger current than when any of the turns adjacent to the zero turn are in engagement with the contactor so that it contactor is in engagement with the zero turn of the resistance wire. The potentiometer card then is clamped in this position in the gaging fixture. A lead connected electrically to the unity turn, which also has other turns positioned on both sides thereof, of the resistance wire is connected to the galvanometer, and a movable contactor connected to the galvanometer may be will be known that the moved along the potentiometer .card until it 1 engages the unity turn of the resistance wire,

' which is slidably mounted on a guideway will be darkened to indicate which position of the contactor is located by the reading of the galvanometer in the manner the -zero turn is located. A contactor carried with the movable contactor breaks a circuit to an electric lamp if the contactor engaging the unity turn of the resistance wire is moved out of a predetermined range with respect to the contactor engaging the zero turn of the resistance wire. Hence, if the linear length between the zero turn and the unity turn of the resistance wire is not within predetermined limits, the lamp that fact.

A complete understanding of the invention may be obtained from the following detailed description of an apparatus forming specific embodiments thereof, when read in conjunction with the appended drawings, in which Fig. 1 is a top plan view of a portion of an ap paratus embodying the invention with portions thereof shown in section;

Fig. 2 is a fragmentary, front elevation of the apparatus;

Fig. 3 is a vertical 3-3 of Fig. 1;

Fig. 4 is a vertical section taken along line 4-4 of Fig. 1;

Fig. 5 is a side elevation paratus;

Fig. 6 is of Fig. 5;

Fig. 7 is an enlarged, vertical section taken along line 1-1 of Fig. 5, and

section taken along line of a portion of the apa vertical section taken along line M Fig. 8 is an enlarged diagrammatic view of the apparatus.

Referring now in detail to the drawings. there is shown therein a gaging fixture Ill (Fig. 1) and a test set ll (Fig.8). The gaging fixture includes a base plate l2 (Fig. 1) and a contactor unit l5, IS. A locking pin I! normally is positioned either in a bushing 20 (Fig. 2) or in a bushing 2| to secure the contactor unit I5 against movement relative to the base plate l2.

The contactor unit l5 includes a steel block 22 (Fig. 3) and an insulating block 25, which insulates the block 22 from the ground. The block 22 is provided with a bore 26, a counterbore 21 and a tapped bore 28. A contactor 30 is mounted slidably in the bore 26 and is provided with a shoulder 3i and a square shank 32. pression spring 35, which abuts the contactor 33 and a threaded plug 35, presses the contactor 30 toward the left, as viewed in Fig. 3, and normally A comholds the contactor 30 in a position in which the shoulder 3| of the contactor abuts a stop 31. The

- therewith. The end of the contactor 30 projects through an opening 4| formed in an edge abutment 42 composed of electrical insulation. and is provided with a narrow line-like tip 45.

A zero turn 46 of an insulated resistance wire 41, which has a very small diameter (of the order .of three and one half thousandths of an inch),

and is wound closely on a body member 50 to form a potentiometer card 5|, is connected electrically to a lead 52, and a lead 55 is connected electrically to a unity turn 58 of the resistance wire 41. To test the linear distance between the zero turn 48 and the unity turn 56 of the resistance wire 41, the zero turn and the unity turn, each of which is positioned intermediate of other turns of the resistance wire, must be located.

- A clip 51 (Fig. 8) is clamped to the lead 52, and the potentiometer card 5| is placed on support 60 (Fig. 3) composed of electrical insulation in a position. in which-the zero turn 46 is near the contactor 30. In this position, an edge 59 of the potentiometer card 5| engages the edge abutment 42 and is engaged by the narrow, line-like tip 45 of the contactor 30. The edge 59 of the card is formed by the closely wound resistance wire 41, and the insulation of the resistance wire is absent along this edge, so that each turn may be contacted electrically. However, the sides of the turns of the resistance wire are completely insulated from one another.

Contactors 5| and 52 (Fig. 8) of a master switch 65 are moved into engagement with 'contacts 56 and 61, respectively, thereof. Contactors 10 and 1| of a double-pole double-throw switch 12 are moved into engagement with a dummy contact 15 and a contact 16, respectively,

thereof. This closes a circuit to a battery 11 and.

current from the battery flows through a protective resistance 80, agalvanometer 8| and a shunt resistance 82 connected in parallel with the galvanometer 8|, a conductor 85, the contactor 52, a conductor 85, the contactor 1|, the contact 15, a conductor 81, a terminal post 90 of the test set II, a conductor 8|, the contactor 30, the portion of the resistance wire 41 between the contactor 30 and the zero turn 48 thereof,- the lead 52, the clip 51, a conductor 92, a terminal post 95 and a conductor 96. The potentiometer card is slid along the edge abutment 42 until the galvanometer 8| has the highest possible reading tion in which the zero turn 48 of the resistance wire 41 is engaged by the line-like tip 45 of the contactor 30. The post I is slidably mounted in a bore I01 in the bracket I05, and liner pins I|0IIO (Fig. 2) secured to the clamp II are slidably mounted'in bores IIl-III formed in the bracket. The clamp I0| has a pair of jaws H2 and I I3 for holding the potentiometer card against the support 60.

Thecontactors and 1| (Fig. 8) then are moved out of engagement with the contacts and 15, respectively, and the clip 51 is disconnected from the lead 52 and is connected to thelead 55. The contactors 10 and 1| of the switch 12 are moved into engagement with contacts H5 and 6, respectively.

A contactor unit |I1 (Figs. 1 and 4) is slidable along a guideway I20, which includes a base plate I2I supported by a plate I22 composed of electrical insulation, which plate I22 insulates the guideway I and hence the contactor unit II1 from the ground. A block I25 of the contactor unit I I1 is provided with a bore I26, a counterbore I21 and a tapped bore I28. A contactor I having a shoulder I3I and a square shank I32 is slidably mounted in the bore I25. A compression spring I35 secured in the counterbore I21 by a threaded plug I35 urges the contactor against a stop I31. The square shank I32 of the contactor I30 fits closely within a square hole I formed in the stop I31, and the end of the contactor I30 extends through an opening |4I formed in the edge abutment 42. A line-like tip I of the contactor I30 engages the edge 59 of the potentiometer card 5| at a point thereon at or near the unity turn 55 of the resistance wire 41. A bolt I46 connects a conductor I41 electrically to the contactor I30 and secures an arm I50 made of electrical insulaion in a groove I5I in the block I25.

The arm I50 carries a conductive rod I52, which is positioned in alignment with a contactor I having a shoulder I55 formed thereon, which contactor I55 is urged by a compression spring I51 to the right, as viewed in Fig. l. A fixed abutment I serves as a stop to limit movement of the contactor I55 toward the right. A contactor I identical with the contactor I55 is provided with a shoulder I66 and is urged toward the left by a compression spring I61. A fixed abutment I10 serves to limit movement of the contactor I65 toward the left. The distance between the shoulder I56 on the contactor I55 and the shoulfor any of the positions of the card- When this reading is the highest, the contactor 30 will be in engagement with the zero turn 45 of the resistance wire 41 so that there will be the least resistance between the contactor 30 and the lead 52 possible for any positions of the card, which causes the high reading of the galvanometer.

After the potentiometer card 5| has been located in a position in which the zero turn 48 of the insulated resistance wire 41 is contacted by the contactor 30, a lever 91 (Fig. 3) is moved in a counterclockwise direction. as viewed in Fig. 3, to the position in which it is shown in Fig. 3. The lever is pivotally mounted on a post I00 of a clamp IN and is provided with cam portions I02I02. This moves the cam portions I02--I02 out of engagement with a bracket I05 to permit a compression spring I06 to urge the clamp downwardly to clamp the potentiometer card 5| between the clamp and the support 60 in its posidef I 66 on the contactor I55. when the contactors I55 and I 65 both are in engagement with the conductive rod I52, is greater by a predetermined amount than the distance between the fixed abutment I 60 and the fixed abutment I1II.

A micrometer adjustment screw I68 having a scale I69 formed thereon may be turned to move the contactor unit II1 along the guideway I20, and a pointer I1| formed on abearing I12 mounting the micrometer screw I58 indicates on the scale I59 the distance the contactor unit H1 is moved along the guideway I20. The micrometer screw I58 is preset at zero with the tip I65 of the adjustable contactor I30 at a known distance from the tip 45 of the fixed contactor 35, and the reading ,of the pointer "I on the scale I55 is the distance the contactor I30 is moved from its zeroor standard point. The contactor unit I" and the arm I50 may be moved either toward the right or toward the left from a central position a predetermined distance from the contactor unit I5, 9. distance sumcient that the conductive rod I52 is moved out of engagement with either the contactor I55 or the contactor I65, depending on which direction the contactor unit 1 and the conductive rod I52 are moved.

The conductor I41 electrically connects the contactor I30 to a terminal post I13, which is connected by a conductor I14 to the contact H6. When the contactors and 1| are moved into engagement with the contacts 5 and 6, as described hereinabove, current flows through the following circuitf the battery 11, the resistance 80, the shunt resistance 82 and the galvanometer 8|, the conductor 85, the contactor 62, the contact 61, the conductor 86, the contactor 1|, the contact 6, the conductor I14, the terminal post I13, the conductor I41, the contactor I30, the portion of the resistance wire 41 including the unity turn 56 of the resistance wire between the contactor I30 and the lead 55, the lead 55, the clamp 51, the conductor 92, the terminal post 95 and the conductor 96. The contactor unit I |I1 then is moved along the guideway I20 until the galvanometer 8| indicates the largest passage of current for any position of the contactor I30 relative to the potentiometer card 5|, in which position the narrow line-like tip 45 of the contactor I30 engages the unity turn 56 of the resistance wire 41.

If the engagement between the conductive rod I 52 and both of the contactors I 55 and I65 has not been broken by the movement of the contactor I I1 and the conductive rod I52 in moving the contactor I30 to its position in engagement with the unity turn 56 of the resistance wire 41, the following circuit is unbroken: a conductor I connected to the contactor I55, a terminal post I16, a conductor I11, an electric lamp I80, a conductor I 8|, the contact H5, the contactor 10, a conductor I82, a secondary winding I85 of a transformer I86, a conductor I81, a terminal post I88, a conductor I89, the contactor I65 and the conductive rod I52. Conductors I90 and I9I of a power-line I92 supply power to the transformer I86 through the following circuit: the conductor I9I, the contactor 6|, the contact 66, a conductor I 95, a primary winding I96 of the transformer I86 and the conductor I90. This energizes the secondary winding I85 of the transformer I86 so that the lamp I80 is lighted, which fact indicates that .the en gagement between the conductive rod I52 and both of the contactors I55 and I65 has not been broken, which is true only when the distance between the zero turn 46 of the resistance wire 41 and the unity turn 56 of the resistance wire 41 is within allowable limits.

If the distance between the zero turn 46 of the resistance wire 41 and the unity turn 56 of the resistance wire 41 is too long, in moving the contactor I30 into engagement with the unity turn 56, the conductive rod I52 is moved to the left, as viewed in Fig. 8, a distance suflicient to cause the shoulder I66 of the contactor I65 to strike the abutment I10 and the conductive rod I52 moves out of engagement with the contactor I65. This breaks the circuit to the lamp I80, which darkens and indicates that the length between the zero turn 46 and the unity turn 56 is not within the allowable limits and that the potentiometer card 5| is not satisfactory. Conversely, if the distance between the zero turn 46 and the unity turn 56 is too short, the conductive rod I52 is moved out of engagement with the contactor I55 in moving the contactor I30 into engagement with the unity turn 66 so that the lamp I80 is darkened in this 6 instance, thereby indicating that the potentiometer card 5| is not satisfactory.

A conductor I88 connected to a terminal post I88 connected to the housing (not shown) of the test set II grounds the housing of the test set for purposes of safety. Thus, even in case of a short to the housing the housing may be touched without danger.

In practicing the invention in accordance with the apparatus described hereinabove, the potentiometer card 5| (Fig. 3) is placed upon the support in a position in which the edge 58 thereof rests against the edge abutment 42 in contact with the contactors 30 and I30. The clip 51 is connected to the lead 52 and the master switch (Fig. 8) is closed. The contactors 10 and 1| are moved into engagement with the contactors 15 and 16, respectively, of the switch 12 and the potentiometer card 5| is moved relative to the contactor 30 to a position in which the galvanometer 8| has its highest reading for any position of the card relative to the contactor 30, in which position the card is properly positioned in the gaging fixture I0 and the unity turn 46 of the resistance wire 41 is engaged by the contactor 30.

The lever 81 (Fig. 3) then is moved to the position shown in Fig. 3 and the clamp |0I clamps the potentiometer card 5| firmly against the support 60 in the position in which it has been located, that is, in a position in which the contactor 30 engages the zero turn 46 (Fig. 8) of the resistance wire 41. The clip 51 is disconnected from the lead 52 and is connected to the lead 55. The contactors 10 and 1| are movedout of engagement with the contacts 15 and 16 and into engagement with the contactors I I5 and I I6, respectively, and the lamp I is lighted.

The micrometer screw I68 (Fig. 1) then is turned, if necessary, until the narrow line-like tip I 45 of the contactor I30 engages the unity turn 56 of the resistance wire 41, which position of the contactor I30 may be determined by the relative readings of the galvanometer 8.I (Fig. 8). If the conductive rod I52 is in engagement with both the contactor I55 and the contactor I65, the lamp I80 remains lighted, which fact will indicate that the distance between the zero turn 46 of the resistance wire 41 and the unity turn 56 thereof is within allowable limits. If .the engagement between the conductive rod I52 and either the contactor I55 or the contactor I65 is broken, the lamp I80 is darkened, which fact indicates that the distance from the zero turn 46 of the resistance wire 41 to the unity turn 58 thereof is not within allowable limits. The actual distance between the turns 46 and 56 may be obtained from adding or subtracting, depending on which direction the contactor I30 is moved relative to the contactor 30, the reading of the pointer I1| (Fig. 1) on the scale I69 formed on the micrometer screw I68 to or from the distance between the tip I45 of the contactor I30 and the tip 45 of the contactor 38 when the micrometer reads zero. The card then may be taken out of the gage and the operation described hereinabove may be repeated to gage the length of another similar card (not shown) The locking pin I1 (Fig. 2) may be moved from the bushing 20,- and the contactor unit I5 may be slid to the right, as viewed in Fig. 2, to a position in which the locking pin I1 is aligned with the bushing 2|. The locking pin I1 may be then inserted into the bushing 2| and the gage may be used to measure the distance between zero turns and unity turns of potentiometer cards, which have longer efiective lengths than that of the potentiometer card 5|.

potentiometer' cards and also determine whether the efiective lengths of the potentiometercards.

are withinallowable physical limits. The apparatus is very accurate, while it is simple in construction and is easy to operate. The apparatus quickly and accurately locates turns of every small resistance wires having leads connected thereto and eliminates the inherent disadvantages oflocating them by unreliable, diflicult and timeconsuming visual inspection methods.

What is claimed is:

l. A gage for determining the distance between two tapped turns of a resistance wire of a potentiometer card, which comprises a stationary contactor for engaging a single turn of a resistance wire of a potentiometer card at a time, a support upon which a potentiometer card may be placed in a position in which one turn of a resistance wire thereof is engaged by the stationary contact and along which the potentiometer card may be slid for movement relative to the contactor, means for electrically determining when the potentiometer card is in a position in which the contactor engages a tapped turn of the resistance wire, means for clamping the potentiometer card in the last-mentioned position, a movable contactor for engaging a single turn of the resistance wire at a time, means for sliding the movable contactor along the potentiometer card, means for electrically determining when the movable contactor contacts another tapped turn of the resistance wire, and means for gaging the distance between the stationary contactor and the movable contactor.

2. A gage for determining the distance between two tapped turns of a resistance wire of a potentiometer card, which comprises a stationary contactor for engaging a single turn of a resistance wire of a potentiometer card at a time, a support upon which a potentiometer card may be placed in a position in which one turn of a resistance wire thereof is engaged by the stationary contact and along which the potentiometer card may be slid for movement relative to the contactor, current-measuring means, means for electrically connecting the contactor to the current-measuring means, means for connecting a tapped turn of theresistance wire to the current-measuring means so that the current-measuring means indicates when the potentiometer card is in a position in which the contactor engages said tapped turn of the resistance wire, means for clamping the potentiometer card in the last-mentioned position, a movable contactor for engaging a single turn of the resistance wire at a time, means for sliding the movable contactor along the potentiometer card, means for electrically connecting the movable contactor to .the current-measuring means, means for connecting another tapped turn of the resistance wire to the current-measuring means so that the current-measuring means indicates when the movable contactor contacts the second tapped turn of the resistance wire, and means for gaging the distance between the stationary contactor and the movable contactor.

3. A gage for determining the distance between two tapped turns of a resistance wire of a potentiometer card, which comprises a stationary contactor for engaging a single turn of a resistance wire of a potentiometer card at a time, a support upon which a potentiometer card may be placed in a position in which one turn of a curately determine the actual eifective lengths of resistance wire thereof is engaged by the stationary contact and along which the potentiometer card may he slid for movement relative to the contactor, means for electrically determining when the potentiometer card is in a position in which the contactor engages a tapped turn of the resistance wire, means for clamping the potentiometer card in the last-mentioned position, a movable contactor for engaging a single turn of the resistance wire at a time, means for sliding the movable contactor along the potentiometer. card, means for electrically determining when the movable contactor engages a second tapped turn of the resistance wire, an electrical signal,

and a switch for actuating the electrical signal and being operable when the movable contactor is moved too closely toward or too far from the stationary contactor.

4. A gage for determining the distance between two turns of a resistance wire of a potentiometer card having leads extending from the turns, which comprises a slide along which a potentiometer card may he slid, a contactor mounted at a predetermined point along the slide in a position pointing transversely with respect to the slide, means urging the contactor transversely of the slide into engagement with a turn of a resistance wire of such a potentiometer card positioned on the slide, a guideway offset from the slide and extending parallel thereto, a second contactor, a carriage mounted slidably in the guideway carrying the second-mentioned contactor in a position pointing transversely with ,respect to the slide, means selectively operable for adjusting the carriage toward and away from the first-mentioned contactor, means urging the second-mentioned contactor transversely toward the slide to force it into engagement with another turn of the resistance wire, a connector for contacting electrically one at a time a lead connected to a turn of the resistance wire near the first-mentioned contactor and a second lead of the resistance wire connected to a turn of the resistance wire near the second-mentioned contactor, means for impressing a potential difference across the connector and the contactors one at a time. means for measuring the resistance between the connector and the first-mentioned contactor so that the tapped turn of the wire may be located in contact with the first-mentioned contactor when the card is moved along the slide. means for clamping the card to the slide in a position in which the last-mentioned tapped turn is in contact with the first-mentioned contactor, means for measuring the resistance between the connector and the secondmentioned contactor so that the second-mentionedcontactor may be located in contact with the second-mentioned tapped turn, and means operable by the slide for indicating when the distance between the first-mentioned contactor and the second-mentioned contactor is within a predetermined range.

5. A gage for determining the distance between two tapped turns of a resistance wire of a potentiometer card having lead wires extending therefrom, which comprises a stationary contactor mounted in a predetermined position pointing in a predetermined direction for engaging the turns of a resistance wire of such a potentiometer one at a time, a second contactor for engaging the turns of the resistance wire one at a time, means mounting the second con'tactor at a position spaced from the first-mentioned contactor and pointing in the same direction as the first-mentioned contactor, means selectively operable for moving the second-mentioned contactor toward and away from the first-mentioned contactor to adjust the spacing therebetween, means operable by the contactor-moving means for indicating the spacing between the two contactors, a slide extending between the contactors for supporting slidably the potentiometer card in a position extending between the contactors and in which turns of the resistance wire of the potentiometer card are engaged by the contactors, a connector for contacting one at a time the lead wires, means for impressing a potential difference across the connector and the contactors, means for measuring the resistance between the connector and the first-mentioned contactor so that the potentiometer card may be moved relative to that contactor until that contactor engages the turn to which the lead wire is electrically connected, means for clamping the potentiometer card against movement after the first-mentioned contactor engages the tapped turn of the resistance wire, said connector, said measuring means, said second-mentioned contactor serving to indicate when the second-mentioned contactor contacts a second tapped turn of a potentiometer card, and means including a limit switch operable by the second-mentioned contactor for indicating when the second-mentioned contactor is moved beyond a predetermined range.

6. A gage for determining the distance between two tapped turns of a resistance wire of a potentiometer card having lead wires extending therefrom, which comprises a stationary contactor mounted in a predetermined position pointing in a predetermined direction for engaging the turns of a resistance wire of such a potentiometer one at a time, a second contactor for engaging the turns of the resistance wire one at a time. means mounting the second contactor at a position spaced from the first-mentioned contactor and pointing in the same direction as the firstmentioned contactor, means selectively operable for moving the second-mentioned contactor toward and away from the first-mentioned contactor to adjust the spacing therebetween, means operable by the contactor-moving means for indicating the spacing between the two contactors,

a slide extending between the contactors for supporting slidably the potentiometer card in a position extending between the contactors and in which turns of the resistance wire of the potentiometer card are engaged by the contactors, a connector for contacting one at a time the lead wires, means for impressing a potential difierence across the connector and the contactors, means for measuring the resistance between the connector and the first-mentioned contactor so that the potentiometer card may be moved relative to that contactor until that contactor engages the turn to which the lead wire is electrically connected, and means for clamping the potentiometer card against movement after the first-mentioned contactor engages the tapped turn of the resistance wire, said connector, said measuring means, said second-mentioned contactor serving to indicate when the second-mentioned contactor contacts a second tapped turn of a potentiometer card.

RAYMOND W. MUELLER. RICHARD STECH.

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